Her Laugh
Only a handful of people had ever heard Sesshoumaru's laugh and lived to tell the tale. Rin, was one of them, of course. He could never intentionally harm his mate. Inuyasha made the list too. That was another story, but Rin didn't want him harmed because he was Sesshoumaru's brother and what not. But then Kagome had heard his laugh too, because wherever that idiot brother of his went Kagome went too. And Jaken. That was it.
He rarely laughed, perhaps once every 6 moons before he met Rin. It greatly pleased her that this number skyrocketed by the time they were mated. In their private home, he would laugh at her faces, and her bad jokes. He would snort and clutch his sides and chuckle for minutes on end. He would never admit to as much. Ever.
But Rin's laugh was musical. It chimed like bells, and made his stomach feel like he was experiencing indigestion. Her laugh made him smile, and he would only accept hearing that laugh for the rest of eternity.